[TriLUG] Disk subsystem recommendations

[Joseph Tate]

Seek times on HDDs AVERAGE 8-9 ms.  The Intel SSD has an 85
microsecond latency (constant time).  The only place where Flash SSDs
do NOT outperform HDDs at this stage is in long sequential writes.
Check out the chart here for relative performance/cost:
http://www.storagesearch.com/ssd-ram-v-flash.html (it's a vendor
suppplied chart, so take with a grain of salt).

On Wed, Nov 25, 2009 at 4:45 PM, Clay Stuckey <claystuckey at gmail.com> wrote:
> The tricky thing is that there are several factors to disk performance. You
> have seek time (how much time it takes to find the data) then you have the
> read/write MB/s that is quoted. This is typically sequential read/writes. I
> expect you will have a mix of sequential and unordered read/writes in the
> real world.
>
> While raid-0 does increase your transfer rate, you are still limited to a
> single spindle. This means your host OS and VM(s) will be fighting for head
> time. I have been running 3 fast sata drives in a raid0 for a while and have
> felt that I should have much better performance. That was until I realized
> that I can only get 1 piece of data at a time. I just recreated my volumes
> as 3 single drives. I have the host os on 1. The other 2 drives will each
> get a vm. I expect I will see a major performance increase for my situation.
>
> If your host/guest machines are performing normal operations (ie: many small
> read/write operations), it would seem that seek time and separate spindles
> is what you need.
>
> I don't know how solid state drives compare with platter drives. Maybe they
> can read/write more than one item at  a time.
>
> I will let you know how my performance works out next week.
>
> Clay
>
>
>
> On Nov 25, 2009, at 4:36 PM, Ron Kelley wrote:
>
>> x2 on the SSDs.  $489/ea for the Intel 160GB G2 SSDs (zipzoomfly.com).
>>  Put a pair in RAID-0 for $1K.  Very fast and should last a long time.
>>
>> -Ron
>>
>>
>>
>> On Nov 25, 2009, at 4:31 PM, Joseph Tate wrote:
>>
>>> I don't think you want the overhead of LVM.  I'd stick with straight
>>> partitions.
>>>
>>> Why not go solid state disks?
>>>
>>> On Tue, Nov 24, 2009 at 10:02 PM, btncix btncix <btncix at gmail.com> wrote:
>>>>
>>>> I don't know much about VMWare nor much about virtualization, but if
>>>> your
>>>> main concern is performance, I would suggest you keep RAID-0 and create
>>>> separate partitions. If you're worried about flexibility with hard drive
>>>> partitions, look into LVM for your root partitions and logical
>>>> partitions
>>>> for your boot partitions. Of course, this more difficult to setup than
>>>> what
>>>> you were thinking about, but it let's you keep RAID-0 and still create
>>>> your
>>>> VMs with direct physical access to hard drive.
>>>> --
>>>> TriLUG mailing list        :
>>>> http://www.trilug.org/mailman/listinfo/trilug
>>>> TriLUG FAQ  : http://www.trilug.org/wiki/Frequently_Asked_Questions
>>>>
>>>
>>>
>>>
>>> --
>>> Joseph Tate
>>> Personal e-mail: jtate AT dragonstrider DOT com
>>> Web: http://www.dragonstrider.com
>>> --
>>> TriLUG mailing list        :
>>> http://www.trilug.org/mailman/listinfo/trilug
>>> TriLUG FAQ  : http://www.trilug.org/wiki/Frequently_Asked_Questions
>>
>> Thanks,
>>
>> -Ron
>> rkelleyrtp at gmail.com
>>
>> --
>> TriLUG mailing list        : http://www.trilug.org/mailman/listinfo/trilug
>> TriLUG FAQ  : http://www.trilug.org/wiki/Frequently_Asked_Questions
>
> --
> TriLUG mailing list        : http://www.trilug.org/mailman/listinfo/trilug
> TriLUG FAQ  : http://www.trilug.org/wiki/Frequently_Asked_Questions
>



-- 
Joseph Tate
Personal e-mail: jtate AT dragonstrider DOT com
Web: http://www.dragonstrider.com